Put brisket in a large Dutch oven; Cover with water and add onion, celery, carrots and garlic. Bring to a boil, cover and simmer for 3 hours. Remove brisket to a cooling rack that’s been placed on a baking sheet and sprayed with nonstick spray.

Strain the cooking liquid through a strainer and return to the pot. Discard the solids. Add cabbage, bring to a boil and simmer about 20 minutes.

Meanwhile, bring another pot of water to a boil and add potatoes; simmer for about 20 minutes. Add optional brussels sprouts and baby carrots during the last 7 to 10 minutes. Drain and add the parsley, butter, lemon rind, lemon juice and pepper.

Preheat broiler.

Combine breadcrumbs and horseradish. Spread mustard over one side of the brisket. Press the breadcrumb mixture onto the mustard. Broil brisket until lightly browned. Watch carefully–this will only take a couple of minutes.